Light emitting diodes (LEDs) are increasingly being utilized as a light source in various lighting fixtures because of their inherently high efficiency in converting electrical power to light. Although LED elements are relatively expensive, compared to incandescent and other forms of light sources, the initial cost is recovered over time through energy conversion efficiencies. A typical LED light source suitable for commercial and theatrical lighting can be comprised of a plurality of individual LED elements arranged in an enclosed housing to discharge light through an output lens or window of a predetermined size and shape. A representative such light source is shown in, for example, the Harbers et al U.S. Pat. No. 7,988,336, assigned to Xicato, Inc., the content of which is incorporated herein by reference.
A frequent requirement of commercial and theatrical lighting is to be able to confine light output of a luminaire or light fixture to a relatively narrow beam, for example as narrow as 8 degrees, so that a particular object can be highlighted in relation to its immediate surroundings. With available commercial LED illumination modules, such as the shown in the before mentioned Harbers et al patent, the light output lens or window covers a plurality of LED elements and accordingly is of relatively large diameter. The emitted light is somewhat diffused in that it originates from a plurality of sources and confinement of the light into a tight beam requires reflectors, typically of a compound parabolic configuration, to be undesirably long in an axial direction. Conventional reflectors thus tend to a compromise, combining a somewhat shorter reflector with a wider-than-desired beam concentration.